Making HIV testing routine is one of the major HIV prevention strategies in the United States. The Centers for Disease Control and Prevention recently recommended that prevention counseling not be required as part of HIV screening programs in medical care settings, except as part of post-counseling for persons who have a positive test result. This policy recommendation has been controversial, and there is disagreement among policy makers, researchers, and public health officials about the need for and effect of routine pre-test counseling with HIV testing. There have been no prospective studies since the implementation of rapid HIV testing in either health care or non-health care settings that have evaluated the effect of rapid HIV testing with and without counseling on acceptance of testing (i.e., increasing the number of persons who learn their HIV status), reduction of risk behaviors and decreasing new sexually transmitted infection including HIV. Within this context, this proposal seeks to adapt our current study that is being conducted under the auspices of the NIDA Clinical Trials Network (CTN). CTN 0032 is a randomized controlled multi-center HIV testing and counseling trial conducted in substance abuse treatment programs to determine the most effective HIV testing and counseling strategy to (1) increase the numbers of persons who know their HIV serostatus and (2) decrease their risk behaviors. Our proposed study will use the infrastructure created in CTN 0032 to conduct the study on a population that is at an extreme high risk for HIV infection: patients at STD clinics. In our adaptation of CTN 0032, we propose to assess the relative efficacy and cost-effectiveness of (1) on-site HIV rapid testing with brief, participant-tailored prevention counseling vs. (2) on-site HIV rapid testing with information only (as recommended in the CDC guidelines). We will evaluate the effect of counseling on two primary outcomes: STI incidence and receipt of HIV test results at 6-month follow-up. Secondary outcomes will be reduction of sexual risk behaviors, substance use during sex, and cost and cost-effectiveness of counseling and testing. We will enroll 5,000 participants at 9 STD clinics in the US. We will conduct subgroup efficacy analyses among persons at highest risk for HIV, including MSM, persons 18-25, and African- Americans. This study will be completed in a 2 year period since we will be using the research infrastructure that has been developed and implemented for CTN 0032, the sites already in place, and the PIs and research teams that have established excellent and productive working relationships. This research was designated as an area of high scientific priority on the NIDA website under the Clinical Trials Network: Increasing the Impact of Trial Results from the NIDA Drug Abuse Treatment Clinical Trials Network. In keeping with the goals of the American Recovery Act, the study will provide economic benefits by employing multiple staff at public health clinics in multiple states, including many of those hit hardest by the recession. PUBLIC HEALTH RELEVANCE: The adaptation of CTN 0032 to include sexually transmitted disease clinics will enable the rapid evaluation of the role of counseling on STI incidence and HIV testing rates in settings that provide medical care to patients at high risk for HIV. Importantly, we will include an economic component of this study that will allow us to determine whether counseling and testing, compared to testing alone, is cost-effective. The results of this study will be used to shape future HIV testing and prevention policies in the United States.